1. Technical Field of the Invention
The present invention relates to a commutation apparatus, and in particular, to a communication apparatus that performs various processes in synchronization with the timing of detecting a boundary pattern that periodically appears in a binary coded signal transmitted through a transmission line.
2. Related Art
It is well known that some communication systems installed in vehicles are configured to use pulse width modulation (PWM) codes as transmission line codes (e.g., see non-patent document SAE-J1850).
In general, when the PWM codes expressing two logical values are decoded, the logical values are determined on the basis of the signal level sampled after lapse of a predetermined period (that is the timing when a signal level differs from one another between the codes that correspond to the respective logical values) from a falling edge (periodically appearing boundary pattern) that expresses a boundary between bits, or on the basis of the results of the measurement of the length of a time duration from the bit boundary to a rising edge (low-level period).
However, these decoding methods have a problem that, if the instantaneously occurring change of signal level due to noises or the like is erroneously detected as a bit boundary, the decoding will result in an error and the communication quality will be impaired.